Satin American etc-12 Q series Trip Units

Merlin Gerin STR (left) and Satin American etc-12 Q series (right)

Sanskriti Engineering has been an accredited installer for the Satin American etc-12 Q-Series trip unit since its introduction to the UK market.  As the Merlin Gerin STR trip units age we regularly see them causing erratic tripping, usually at low load, when a site is not expecting it.  A cost effective solution to this problem is to replace the faulty STR trip unit with the Satin American etc-12 Q series trip unit. The STR trip units are most commonly found on Merlin Gerin Masterpact ACB’s, but can also be branded as a Moeller XZM and Square D in certain circumstances. The Satin American etc-12 Q series trip unit is a viable replacement or upgrade for them all.

Many units have been fitted by Sanskriti Engineering across the UK, helping our many clients’ facilities eliminate nuisance tripping. This enables an upgrade to a mechanically sound ACB (as opposed to changing the entire breaker), and resumes power both quickly and efficiently after an STR unit has failed, by having Satin American units in stock and ready to fit.  The Q-Series is an ideal solution in scenarios where power is unable to be reinstated with a faulty STR unit. This will ensure that an existing good condition Merlin Gerin Masterpact breaker is updated to prevent costly and disruptive downtime.


The Satin American unit can be fitted effectively in a short space of time and uses the same plug type and format as the original equipment. Our qualified engineers can have the new unit fitted, set up, secondary injection tested and power restored in approximately 30 minutes!

Satin American full function Secondary Injection Test set

It is a suitable replacement for Merlin Gerin STR28D, 38S, 58U and 68U trip units on Masterpact breakers.  The Q-Series trip unit offers today’s levels of set up options and can give more adjustment and function than the STR unit it replaces.  Once fitted to a Masterpact (or Moeller XZM/Square D branded) air circuit breaker, the trip unit is secondary injection tested with the Satin American test set across each phase individually as well as ground fault if fitted; proving the protection.

The Q-Series also benefits from being adaptable to different frame sizes (3 or 4 pole) and is able to be rated to suit any Masterpact breaker as it does not require a rating plug. As a consequence it can also then be moved and used on another breaker if required. Another advantage is its compatibility with neutral sensors in residual ground fault protection schemes.

Availability and Lead Time

An STR and Q series side by side showing the same plug type and format which make them “plug and play” and interchangeable within 30 minutes!

Sanskriti Engineering can usually supply, install, set-up and test Satin American etc-12 Q series trip units with immediate effect, as we carry a maintained stock level at all times. The etc-12 Q series can be programmed exactly to the settings of your old STR, with the added compliment of being programmable via its front panel control buttons and including an LCD display for viewing both settings and trip events. It can also give a “live” display showing current per phase for monitoring and pick up indication.

For further information or technical advice regarding  STR and Satin American trip units, you can contact us here.